It was the year 1963.  The inquiry came from a third year secondary school boy. He was Ernesto B Mpemba   in Tanzania. His teacher just refused to believe him and his class mates just laughed at him.

Some of his friends , who were making ice cream along with him confirmed what he believed in . He decided to investigate the phenomenon further.  

During this time, Dr. D.G. Osborne from the University of Dar es Salam  delivered a lecture to this class.   When it was the question time Mpemba promptly raised his pet question.  Although the learned doctor did not believe in the fact, he in order to encourage the inquiry habit of students, politely said that he try it himself before producing an answer.

This led to an article published in a recognised journal in 1969  under the names of  Dr Osborne and Ernesto Mpemba.
Now the effect has come to be known as Mpemba effect.
It has come to light now that this effect had been baffling many a scientist from the earliest times.  

“The Royal Society of Chemistry offered £1000 to the person or team producing the best and most creative explanation of the phenomenon by which hot water sometimes freezes faster than cold water, known today as The Mpemba Effect,”