Generally, objects with low density will float on objects with high density. Eggs are denser than water, so they will sink to the bottom of the water. However, the density of salt water is higher than that of water, and the density also increases with the increase of salt content in water. So when the salt in the salt water reaches a certain level, the density of the salt water will exceed the density of the egg, so that the egg will float.

If the volume of an egg immersed in a liquid is constant, the greater the density of the liquid, the greater the buoyancy of the egg. When buoyancy is greater than or equal to gravity, the resultant force of eggs will be upward. According to the principle of force balance, an egg needs a pair of balancing forces to maintain its original stable state, so the egg will float to reduce the buoyancy generated by the liquid. Eggs will not be floating or suspended until buoyancy equals gravity.