Freezing Water

Every physics major (and perhaps every chemistry major) learns that hot water freezes faster than cold water, even if the reason (according to the laws of thermodynamics) isn't clear. The story I heard was that Fermi, Bethe, and those kind of guys were sitting around at a conference when a waiter happened to mention that hot water in the kitchen froze earlier than did cold water. Did they know why? They started calculating entropies and conservations of energy and tried to explain the phenomenon, but the actual reason seems quite simple: hot water precipitates out solvents which then act at points of freezing. In any case, the answer isn't as simple as you might expect. New Scientist explains it all here.