Never remove the radiator cap when the engine is hot, as the hot coolant will be under pressure. Also, be aware that an electric cooling fan can come on at any time.
A belt or hose failure can cause an overheated engine, loss of power steering, and loss of the electrical charging system. If a hose leaks coolant or the belt turning the water pump snaps, the cooling system is inoperable. If the engine overheats, it can suffer serious internal damage that requires expensive repairs and can ruin a summer holiday.