CAUTION: Chlorine Gas is formed, do this in a well ventilated area.
This is a very similar procedure described in the Extracting Hydrogen and Chlorine from brine experiment but this will make 2 useful byproducts.
Set up the apparatus as shown with brine (table salt dissolved in water) as the electrolyte. The brine soaked rag joining the two jars are to allow a current to pass through without contaminating the different the byproducts formed in each jar.
Chlorine will form from the anode and dissolve into the newly formed sodium hydroxide to produce sodium chlorate.
The cathode will bubble hydrogen gas and form pure sodium hydroxide.
When the reaction is complete no more bubbles will form and you'll have a jar of homemade bleach (sodium chlorate) and home make oven cleaner (sodium hydroxide, or commonly called lye)