This is a classic early elemtrey experiment because it is easy and it is fun.
First take an uncooked egg and plop it in a glass or jar of water. Watch it for a bit and see it form bubbles as the calcium in the eggshell is starting to dissolve.
I know it looks like James is about to take a drink of the vinegar, but actually he is trying to get a closer look at the egg, and smell the vinegar.
After about a week the egg will look like this.
The shell disappears entirely and all you have left is a little membrane.