Don't feel too bad, I know adults who behave like this: stew silently about their job until all they can do is rage-quit, stew silently about their marriage until they scream at their spouse, etc. The behavior has the detrimental effect on their lives you'd expect (which is why it's so great that you're identifying this early and trying to get a handle on it).
It will be difficult to answer this definitively without more detail but it's definitely a communication-skills problem from the following (non-exhaustive) list:
He expects people around him to constantly query his internal state (you should be asking me if I'm ok, how I feel, etc.). You will need to work at getting him to understand that others have the same avalanche of thoughts, feelings, and responsibilities: sparing attention for others is an effortful activity and the world does not revolve around him.
He expects people to read his mind (if you really loved me you'd just know how I feel). This scenario is very similar to the first, with the same tack of convincing him of the unreasonableness of his expectations.
He believes that life is fair, and cannot handle evidence to the contrary as it challenges a core belief. Note that this one may seem very different from the two above, but is actually quite similar in an important way. It could be that he thinks the world is fair and it is the responsibility of authority figures (including parents and teachers) to enforce it. The problem is that the locus of control is still external (centered on authority figures).
In any case, it's clear your son has (at least one) unreasonable expectation about how interpersonal communication works: you are going to have to model and encourage appropriate communications (especially if you notice a potential problem brewing). You will also have to reinforce that temper-tantrums are not appropriate, ever. Rage-quitting no matter what the provocation is unacceptable.
Just make sure that any punishment includes walking through the chain of poor decisions that led to explosion lest he resent it as more unwanted evidence of unfairness.