That's why I always tap a long spoon on the surface of the cup from as far away as possible to break the surface which if it were super heated would cause it to explode rather than putting it down on my counter and staring down at it so it can explode right in my face and all over my body.
With my method, at the worst it might get my hand a little, but potentially not even that.
It only really happens if you're using a brand new glass container that is like almost perfectly smooth and bubbles can't form. If you have an older mug you've heated plenty of times before without it exploding then you can pretty much assume it should be fine. I still test it every time anyways...
