Why does gum get stiff immediately when you drink water but not when you chew and add saliva?
In:
Saliva and your mouth chewing are at a warm temperature. The water you drink causes the “hardening” by being cold in comparison. Try the same with hot water.
The water you drink is almost always cooler than body temperature. The cold makes it hard, not the wet.
Temperature? Water is usually colder than your own spit. I think that has something to do with it.