Sylvia Bloom wasn't born into wealth: The 96-year-old, a child of Eastern European immigrants, grew up in Brooklyn during the Great Depression and put herself through college at Hunter. But at the end of her life in 2016, her family and friends learned something about her that she had been keeping quiet for years: She was a self-made millionaire — and she was donating her fortune to good causes, according to a report in The New York Times.

Bloom, who made her money by both investing wisely and living modestly, distributed more than $8 million in her will. A total of $6.24 million will go to the Henry Street Settlement for disadvantaged students, the largest single donation from an individual to the group in 125 years, the Times reports. Another $2 million will be split between her alma mater and an additional scholarship fund that's yet to be announced.

When the extent of her fortune became clear, it surprised even some of the people closest to her, Bloom's niece Jane Lockshin tells CNBC Make It. Lockshin is also treasurer of Henry Street's board and executor of Bloom's estate.

"I was flabbergasted! I know Sylvia had enough money to live on but I did not know the extent of her estate," she says. "My aunt was a very private person and never mentioned the extent of her estate to anyone. She probably thought that was no one's business but her own."