Your UI isn’t a Disney Movie
Sophie Paxton

I believe you might mean “back-out” here, which is an elastic spring like animation. Ease-in-out is a very straightforward sine curve, which is as basic as it gets while still looking natural. (Note, ease-in and ease-out are distinct easing equations, which also look natural depending on the circumstance).

You can play with several examples here: http://robertpenner.com/easing/easing_demo.html