While most cats keep purring throughout their lives, not all cats actually keep kneading beyond kittenhood, according to Armour. But many continue - and some get really into it. Some cats get so into their kneading trances that they even start drooling. And there's actually a sort of heartbreaking reason for the dribble.
"In my experience, this is often seen with orphaned kittens who were bottle-fed by humans, or kitties who were weaned too young," Armour said. "They still have that vestigial connection between kneading and suckling that many other cats have outgrown."