...How...does one burn soup?
Well you don't Burn the liquid bit per se, But like if its a 'heavy/chunky' soup, if you don't stir the pot enough, the suspended solids (veggies? meat... cream/milk etc ) can settle down.. and get burnt on the bottom of the Pot! This is why you have to keep stirring it!
Edit: actually... not just the solid stuff settling on the bottom.. but if its the thick soup (ie anything thicker than plain water) convection alone wont keep the liquid evenly mixed, resulting in the soup at the bottom burning!
Another way is... all the water boils off and then everything burns.. but thats less likey!