Sounds like your girlfriend might have anger issues she needs to speak to a therapist about. Outbursts like that are a MAJOR sign there's hidden issues under the surface that just talking with her are not gonna be enough to fix.

I would say you need to approach the situation delicately when she is in a good mood (so that there's less of a chance for a blow up) and say something along the lines of "listen hun I'm really worried about you and I think it would be best if you spoke with a professional about it, I'm always here for you no matter what but I think it would be better for both of us if you got some help"

I wish you two the best of luck!