One thing which differentiates us from Robots is Our emotion. Emotions play a key role in how we respond to challenges. Our emotions can make or break our relationship or formal alliance. We are not Socrates to remain logical or rational on all occasions.
Emotional outbursts lead to an argument and act as a sign of incompetence or weakness.
On a receiving end one should deal it with empathy and care. Understanding the core issue for the outburst can help. Listening others without arguing also clears things.
Having a clear picture and end goal of working together and navigating through emotional outburst can be comforting.