Microwave Randomly Trips Circuit Breaker?

The microwave in our kitchen trips the circuit breaker at random. We can be using the microwave for five days, and it won't trip it. Then, we can just close the microwave door, at other times, and that will trip it. We have a 10A circuit breaker.

Can I change that one for a 15A? I've already replaced the 10A once and it still continues to do the same. We've isolated the problem to one outlet; there's two outlets connected to that circuit breaker, but there's nothing connected to that second one, it's outdoors. And, there's nothing else connected to that outlet or circuit breaker.

Any assistance would be great.

By Joey Z.