Ever worked in a company where all your colleagues quit en masse, nobody wanting to be the last man standing and saddled with the work of his departed colleagues?

In these situations, there's usually a common thread: the employer is left scratching his head wondering why the hell everyone walked out, eventually rationalising that the employees left due to greed or personal reasons.

Meanwhile, all the employees know very, very well why they quit. And it's usually down to one of these four reasons.

1. AT LEAST ONE OF THE BOSSES IS INSUFFERABLE

I cannot stress how many times people I've worked with walked out on the company because the boss was driving them nuts.

Yet bosses never seem to realise that they are the ones driving employees away.

A sure sign that a boss is to blame for resignations is when you have one team under a particular boss whose people keep quitting, while other teams have a much lower turnover rate.

Nigel, a 32-year-old lawyer says, "My boss practically drove me out of the firm with his ridiculous and dramatic behaviour. I had been planning to stay in this particular job for much longer, but finally felt that I had no choice but to leave."

2. THE WORKLOAD IS TOO HEAVY

No matter how many lifestyle perks a company doles out and how many Employee Appreciation Days it organises, expect a high turnover rate if the workload is too heavy.

More and more employees are starting to be wary of companies that require them to work very long hours, especially as we are one of the worst countries in the world in terms of work-life balance.

Evangeline, a 30-year-old legal counsel, habitually worked till midnight every day in the first two law firms she was employed at.

She has since quit working at law firms altogether and is now a legal counsel at a local bank.

She says, "The turnover rate in the legal profession is very high as not everyone can handle the punishing hours. While long hours are unavoidable in law, it is also the firm's choice to get by with fewer rather than more associates. Since so many associates are willing to burn the midnight oil and stay at the office overnight, why try to hire more people?"

3. IT'S A DEAD END JOB OR A FAMILY BUSINESS WHERE CRONYISM IS RIFE

If there's one thing employers should understand about young Singapore employees, it's that professional growth is very important to them.

Nobody wants to be stuck earning the same salary three years from now, especially not when the cost of living keeps rising.

That's why a lack of prospects at work is one big reason employees leave.

Victor Lim, a 66-year-old retiree, advised his 28-year-old daughter to quit a previous job because she was working for a family business where promotion prospects looked bleak. The company preferred to promote family members who were working there over other staff.

"In family businesses, management will always favour their family members and you will never get ahead," he says.

Family businesses in Singapore tend to have a hard time holding on to employees, as they're viewed as difficult to make progress in, since key positions are usually reserved for family members.

4. THE PAY IS POOR

While some employees can afford to take on a lower paying job because of benefits like flexibility or better work-life balance, in the absence of such perks, expect a high turnover rate.

When Nadine, a 34-year-old civil servant, began her career, she was working in media and getting paid $1,800 a month. She regularly worked till 8pm and beyond, which means she was being paid less than $10 an hour.

The university graduate left one year later for a new job.

"I was okay with the job actually, she says. "But the pay was just too low."

No matter how wonderful a job is, most people go to work to earn money at the end of the day, so employers who are not paying a fair wage should expect their employees to jump ship once they find something better.