The analogy I've seen which I like is to that of a boiling pot of water on a stove. As you increase the heat (energy) in the system, the water level fluctuates

The analogy I've seen which I like is to that of a boiling pot of water on a stove. As you increase the heat (energy) in the system, the water level fluctuates throughout. You have points where there's a higher water level, but you also have points where there's a lower water level.