Hot water freezes faster compared to cold water, due to the intermolecular bonding between water molecules, based on a study conducted by the Nanyang Technological University in Singapore. This phenomenon is known as the Mpemba effect.
The Mpemba effect derived its name from Erasto Mpemba, a Tanzanian student who discovered that a mixture of heated ice cream freezes more quickly than a cold ice cream mixture. A team of physicists from the Nanyang Technological University attributed this occurrence to the hydrogen bonding of water molecules that affects the covalent bonding between the hydrogen and oxygen atoms that comprise a single water molecule. The way energy is stored in these bonds in warm water allows it to release energy and freeze faster compared to cold water.