Science experiment-eggs, water and salt

Yesterday and today we carried out a science experiment.  We had some tap water and lake water. Also we had some eggs.  Everyone made predictions on what they thought would happen when we added the eggs. We carried out some writing about our predictions.
Today we did the experiment-most children thought the eggs would float or sink.
They sat on a side of the classroom.  One side was if they thought it would float and the other side was if they thought it would sink.
Then we added salt-we added 3 teaspoons but nothing happened when we added the egg.
So we thought about adding more salt.  This time we added 9 teaspoons of salt. When we added the egg this time it floated around and around the container.  Everyone thought it was magic!!!