Asset bubbles in shares and property could burst in the next six to 18 months, according to one of the country's more bearish investment experts, who is warning baby boomers that their retirement savings are at risk.

Australian shares, which finished trading at a seven-year high of 5958 points on Monday afternoon, are now only a whisker away, or another rate cut, from hitting a fresh high of 6000 points, a place they have not visited since financial markets collapsed in the wake of the global financial crisis.

Asset bubbles are putting retirement savings at risk. Credit:Tamara Voninski

Property prices in the country's most popular capital cities are also testing new highs, despite rising unemployment and soft wages growth which have worsened housing affordability.

Roger Montgomery, of Montgomery Investment Management, believes asset bubbles are likely to pop in the near future and that "there is a real chance that Baby Boomer retirement plans may sink, thanks to their inability to avoid repeating the investment mistakes of their past".