Suggest going to counseling or just talking to someone about what is causing the anger problem. Someone experiencing this type of anger out of the blue may not even know what it is that is angering them, or they could just be angry with themselves and it causes them to take it out on others. If they refuse to get help or to find what the issue is I ,myself, would walk away from them for good (if it was a significant other) because it can only but you at risk for Domestic Violence, whether it be mental or physical abuse. You can not stop someones anger problem, the person themselves has to overcome their anger problem. Others can offer support, but if the support is denied they chose to face it alone, and you should not feel guilty. Just let them know you will still be there when they have it figured out!!