I was talking to my father about his auto-off coffee maker and he mentioned that turning it on while empty is bad even though it will turn back off on its own because heating up while empty is worse than heating up until all the water evaporates.
His reason for this was
If filled, the heating element's temperature rises much slower; at the end it jumps from about 95 °C to 105 °C, then turns off. Without water, the temperature rises very quickly from 20 °C to 105 °C, and even though at this point the machine turns off, the heat keeps rising due to momentum, up to like 120 °C or so.
This seems very strange to me since as soon as no electric energy is available any longer, where would the energy for an an additional increase in heat come from? Certain parts of the heating system might get hotter, but as a whole, shouldn't it immediately start to cool off?