Have you heard of the Mpemba effect? No, didn't think you would have.
Erasto Mpemba was a Tanzanian schoolboy in 1963 when he informed his science teacher that he could make ice-cream faster by putting hot milk in the freezer than when he used cold milk. He was laughed at for his troubles. The findings were confirmed by school inspector Denis Osborne, and the two published an article on this phenomenon in a peer reviewed journal in 1969.
Apparently, the effect is due to super-cooling of water. Cold water doesn't strictly freeze at 0 degree Celsius- it often takes much lower temparatures before it finally turns into ice. OTOH, hot water is not subject to supercooling. It needs to get only to 0 degrees to freeze. Thus, the rapidly cooling hot milk freezes faster than the cold milk, which lingers around the freezing point of water for a while.
The Mpemba effect is not always reproducible. Apparently, it only works under certain conditions.
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