Modern science has opened our eyes to the many mysteries. Answers to many questions. But sometimes these questions from the category "asked themselves - have answered - and what to do about it, hell knows." That is, on the practical application - it's not us. We do not deal with such nonsense. We solve strategic issues. But sometimes a simple, seemingly question, the answer can not be found for decades.
For example, in 1968 a student from Tanzania Erasto Mpemba asked the question in a lecture Professor Denis Osborne. A simple question: "If you put in the freezer for two vessels - with hot and cold water - it will freeze a container of hot. Why? "But the professor was not able to answer it. He then published an article by conducting research (present process). Called this phenomenon "Mpemba effect" And the answer is never received. As well as to date no one knows the answer to this question.
By the way, like the ancient Greeks knew about this effect and also did not find an answer. And no standard physical effects of this phenomenon can not be explained.
So if you want to cut some money in an easy, there is a great opportunity. Royal Society of Chemistry promises a prize of a thousand pounds (fifteen thousand dollars at the exchange rate) for the disclosure of this puzzle.