Why do you add sugar last when boiling soups? When I read recipes involving boiling a soup/dessert and adding sugar, they often say to add the sugar towards the end of the boiling.  Why is that?  Are there consequences of adding sugar early?
To add onto Walter's answer, adding sugar towards the end for taste when boiling ensures that the sugar dissolves faster so that the results of your addition are more accurate and immediate.  

If you added the sugar before boiling, you run the risk of adding too much sugar because you tasted it before all the sugar dissolved and you added more as a result.