I would recommend you ask for a referral to have your son evaluated by a pediatric neuropsychologist and that, if possible, you find one who has some experience working with high IQ kids with disabilities.
Totally agree with this. Until you know what's going on, you don't know how to solve it or even what educational placement is going to work the best.
Bzylzy also nails it with the idea that this is an escape behavior. Also hard to fix until you know what's going on. You can request that the school do a Functional Behavior Analysis to see when the blowups happen, what preceded them, what the triggers are likely to be. They need to take data if they want answers. It would not be a bad idea to request that the school do a complete educational evaluation, either; this starts the process for getting legal protections in place.
What you describe is not atypical of kids with autism spectrum disorders in the early elementary years; lunch and recess, which are less structured and highly social, do provide lots of extra stressors. Not saying this is necessarily ASD, just saying that you should be looking closely to see whether you can get good answers about your kid's profile.
DeeDee