There's enough nucleation points, even in a pyrex measuring cup, to avoid superheating, as long as you're just bringing it to a rolling boil at maximum (so like 3 minutes, tops), and then using it.
The real problem comes when you microwave the water for three minutes, forget about it, then microwave it again. The nucleation points you had the first time around are now too few. Now when you pour the water into another vessel - or even just jog the water in the existing vessel - it can suddenly and explosively boil over.