Investigations were carried out in a science lab to explore the topic of chemical and physical changes. investigation a step 1. add 5 tsp. salt to 100 ml warm water and stir until most or all of the salt is no longer visible. step 2. heat the salt solution on a burner until only a white solid remains. investigation b step 1. mix 10 tsp. white sugar into 100 ml water and stir until most or all of the sugar is no longer visible. step 2. heat the sugar solution on a burner until the solution thickens and turns brown.