Most of an egg is water.
The nearly colourless liquid in the egg is a solution of proteins.
* Mix 5 ml of the colourless egg liquid with 10 ml water, in which you had dissolved a spatula  of salt before.
* Left: Blow into a sample of this diluted solution:
Observation:  The solution of protein foams, protein molecules act like soap reducing the surface tension of water. (If you want to mix plant oil and water to have a mayonnaise take the liquid in the egg).
* Right:  Distribute this solution on 4 vials.
* Vial 1 is left untreated as control.                       * Vial 2: heat by a micro burner.
* Vial 3: Add some drops of hydrochloric acid.  * Vial 4: Add some drops of copper sulfate.
Observation: By heating and by adding acid and copper sulfate solution a solid is formed.
Explanation: The dissolved protein molecules are damaged by heat, acid and heavy metal salts.