Choose a suitable saucepan for the quantity you need and fill it with water. You should then put it on the hob. Turn the hob on to its highest setting. You will know when the water has boiled as you will see lots of bubbles in the liquid. The same applies when boiling other liquids such as sauces. Watch for those bubbles and then you will know it has boiled. Make sure you are always watching what your child is doing when you have boiling pans.