Why outlets spark when unplugging - EMF & Inductors

I was always told an inductor is like stirring water in a mug with a spoon. Lots of resistance initially or when changing direction (AC electricity  - high impedance at high frequency) but once it's got momentum it has low resistance (inductors behaves like short circuits at steady state DC).
So back EMF is you suddenly stopping the spoon and feeling that resistance as the liquid is forced to stop too