When a male bends a female over into a position called Doggy Style, the male pumps her pussy and fills her up with air (instead of his dick 🙄)at the same time. When the male continues to thrust the female in Doggy Style, the air will 'Pop' in her vagina, thus, making the pussy pop.
Pussy popping is when ur girl stuffs a huge string of pearls in her pussy and gives u the end. As u walk backwards slowly the pearls come popping out of that pussy 1 by 1.