Denser salt water makes the eggs to float in the water.
Explanation:
Egg will always sink in water, as egg is denser than water.
But we can make it to float by means of adding excess salt to the water. Adding more salt to water makes it as denser than egg. Denser water makes less dense egg to float in water.
So, making the water as denser one leads to the floating of egg in the water.