> the actual occurrence of the Mpemba effect is a matter of controversy
> In 2016, Burridge and Linden defined the criterion as the time to reach 0 °C (32 °F; 273 K), carried out experiments, and reviewed published work to date. They noted that the large difference originally claimed had not been replicated, and that studies showing a small effect could be influenced by variations in the positioning of thermometers: "We conclude, somewhat sadly, that there is no evidence to support meaningful observations of the Mpemba effect."
> In controlled experiments the effect can entirely be explained by undercooling [water may cool below the freezing point without actually solidifying] and the time of freezing was determined by what container was used.
https://en.wikipedia.org/wiki/Mpemba_effect
> the actual occurrence of the Mpemba effect is a matter of controversy
> In 2016, Burridge and Linden defined the criterion as the time to reach 0 °C (32 °F; 273 K), carried out experiments, and reviewed published work to date. They noted that the large difference originally claimed had not been replicated, and that studies showing a small effect could be influenced by variations in the positioning of thermometers: "We conclude, somewhat sadly, that there is no evidence to support meaningful observations of the Mpemba effect."
> In controlled experiments the effect can entirely be explained by undercooling [water may cool below the freezing point without actually solidifying] and the time of freezing was determined by what container was used.