What does it look like when a pregnant spider explodes babies?

I have been hearing and read some things that when a pregnant spider is squished,stomped on,or anything else that would kill it naturally,babies come out and I have never seen this before.What I want to know is when the mother is pressed harshly on,there are a lot of multiple of babies coming out,if so is there an average amount?what do they look like when they crawl out?etc.