To keep this really short, the following code crashes MATLAB on my machine:
X = ones(100, 100);
A = X*X;
One could argue that, perhaps, MATLAB should not handle something like ones(1000000,1000000) that well; I think it should, but perhaps some reasonable size limit is acceptable. But the above is trivial; I can't imagine why it's crashing. Other similar examples result in a crash. Multiplication is what's causing the problem (e.g. addition is fine). It's related to size -- a 5x5 matrix works with no problems. And the instantiation of the matrix is also fine; I can even construct much larger matrices with no issues.
My MATLAB is version 2015b. I'm happy to supply whatever other information is relevant.