The rumor persists that hot water will freeze faster than cold water. It sounds implausible because the hot water has more internal energy which must be removed before it can start the phase change .
Ice acts as an insulator , inhibiting the cooling process.
Supercooling to -5 C or lower is cited and it is suggested that both the initially hot and the initially cold water supercool. If the cold water supercools more, then the the hot water may in fact freeze quicker with nothing more than the degree of supercooling to distinguish the two samples. It was also pointed out that the degree of supercooling is not easily predictable, since it probably depends upon tiny particles or bubbles which nucleate the crystal formation. Experiments showed different amounts of supercooling for the same sample when it was repeatedly liquified and refrozen. When Hot Water Freezes Faster Than Cold, Am J Phys.