Subject: Why does a vinegar/water solution freeze before just water?

I did an experiment to see which froze first, water, water mixed with 
vinegar, water mixed with soap or water mixed with salt.  I thought that 
water would be first because the freezing point of the solutions would be 
lower so it would take longer.  What happened was the vinegar and water 
froze solid first, followed by the soap and water and then the water.  The 
salt solution remained slushey.  Why did the vinegar and soap solutions 
freeze first?

Re: Why does a vinegar/water solution freeze before just water?