DonNichols/E+ via Getty Images
Don’t try to boil a mug of water in the microwave. The water superheats but is unable to physically boil because the vessel remains cool, so when you try to stir it or add a teabag it boils all at once, exploding upwards, right in the direction of your face. If you must microwave water, stick a stirrer or something in it so it can boil as usual.
If you put bread in a microwave you won’t end up with a ruined microwave, just a ruined piece of bread. After more than 10 or so seconds in a microwave, enough moisture leaves the bread to make it a hard, stale, chewy mess. The best way to bring back stale bread is to stick it in the oven for a few minutes.