Three Boxes with Two Balls Each Puzzle

The Puzzle:

Three Boxes with Two Balls Each

The first box has two white balls. The second box has two blue balls. The third box has a white and a blue ball.

Boxes are labeled but all labels are wrong!

You are allowed to open one box, pick one ball at random, see its color and put it back into the box, without seeing the color of the other ball.

How many such operations are necessary to correctly label the boxes?

Do you have the answer? Check against our solution!