Help me remember this movie please!?

I don't know very much about this movie except for the fact that the main character was a young girl, and there were 3 witches as well i believe. I only remember a few scenes of the movie. One in which a kid has a sore throat and she starts coughing up frogs while she is on stage performing, and another was at the very end of the movie the evil lady gets stuck in a mirror and then it shatters into a million pieces.. It was more of a light, almost comedic movie. I remembered another part where one of the lady's gets turned boneless, so she's just wiggling and sliding all over the place and she's paper thin...