Rice Cookery in water containing sugar versus plain water
I had some fun with this one. To start: Gelatinization is when the intermolecular starch bonds break, see Starch Gelatinization 

I originally thought it had to do with the sugar changing the boiling point of the water. I thought this would increase cooking time, but turns out that's wrong. A higher boiling point means the water can get hotter before turning into water vapor. Therefore shortening cooking time. The mystery continues. 

Under the last paragraph in section 8.2 of Thermodynamics of Water it talks about impurities.

Shortly after that I found help in this paper Effects of Sugar on Starch Gelatinization. It says that there are two reasons that I'll summarize here. 1) Sugar bonds with the water making it less available to bond with the starch. This makes it so that the water needs to be hotter to bond with the starch. 2) The sugar bonds with the starch holding them together a bit longer.