Mpemba effect still raises strange questions.

The Mpemba effect is the observation that very hot liquids or colloids can freeze more quickly than colder ones, for similar volumes and surrounding conditions.

The Mpemba effect is the observation that very hot liquids or colloids can freeze more quickly than colder ones, for similar volumes and surrounding conditions. Physicists remain divided on the effect's reproducibility, precise definition, and underlying mechanisms. It is named after Erasto Mpemba, a Tanzanian teenager who studied it scientifically in the 1960s for the first time, along with Denis Osborne.