Why does activated charcoal pop and crackle when water is poured over it?

Chemically, oil is long chain fatty acid with two components; hydrophilic —COOH end and hydrophobic long chain hydrocarbon end.

When water is spilled on oil at normal temperature, water spread on oil like a sheet, attracting the hydrophilic —COOH part.

When oil is heated on pan, the intramolecular space increases providing more space of water to get in between. As temperature of oil is above its boiling point, water droplets evaporates quickly and its surface area increases. Lot of hydrogen bonds form between water molecule and oil.

Due to evaporation, tiny droplets try to escape from oil surface and on there way out they carry oil molecules as well. As these gas globules absorbs more heat, they shoot away from oil surface like a jet, breaking all the bonds it formed previously.

This causes cracking sound and spillage of oil droplets.

/r/askscience Thread