Fill a round bottom flask with a coloured liquid up to the brim. Fit it with a one holed cork and pass a narrow glass tube through it. Mark the level of the liquid in the glass tube. Place the flask in a water bath and heat the bath. You will see that the level of liquid water rises in the glass tube. This is due to the expansion of the liquid on heating.
Concept: Graphs Showing Variation of Volume and Density of Water with Temperature in the 0 to 10°C Range