(I) Adding sugar to a drink taken straight from a microwave can trigger an eruption of boiling liq uid. (II) Heat may be transferred from one place to another by conduction. (Ill) The cause of such in- cidents is uneven heating by microwaves, which leads to some parts of the liquid being super- heated beyond their boiling point. (IV) If just a few grains of sugar are then added to this unstable mix, they act as nucleation sites for bubbles. (V) It is these bubbles that form with explosive violence.