Car turns over fine but makes popping sounds while running. on 2001 Plymouth Neon

Recently car came to a sudden stop while driving around 25 miles per hour.Would not move engine still running.Turned engine off and tried to restart but would only make a popping sound.Found out water pump froze and damaged timeing belt though it didnt completely break it was missing a few teeth and had a slit in it.Replace belt and pump now car starts ok but pops while it is running.Why is that?

Asked by for the 2001 Plymouth Neon
timing belt sounds like it off marks.