Hot water freezes faster: It is a physical reality

Water or H2O is a pretty simple and the most commonly available liquid to mankind. Water though is the foundation and elixir of life yet scientists haven't cracked its mechanism of action.

This strange phenomenon was described by the likes of Aristotle, Bacon, and Descartes, yet is named after the Tanzanian high-school student who accidentally discovered by a high school student while freezing a hot ice cream mix in his cooking class in 1969. The Mpemba effect only occurs under very specific sets of conditions still remains a complete mystery.

Scientist show that there are some possible explanations for this phenomenon like differences in supercooling, evaporation rate, frost formation and effect dissolved gases have on hot and cold water. But these are just theoretical explanations but the reality is much more complex than just this.  

This concept is however helpful in large scale manufacturing of ice creams all around the world. How interesting is that!

Reference:

1. J.Walker, “Hot water freezes faster than cold water. Why does it do so?,” Sci. Am. 237(3), 246–257 (1977)
2. M Jeng, "The Mpemba effect: When can hot water freeze faster than cold?",  Am.Jour.Physics 74 (6) 514 (2006)