Who knows about crystal formation?

I'm doing this chemistry experiment where I form crystals using distilled water and sugar in one solution and vinegar and sugar in the other. Within a few days of the experiment the sugar and water began to crystallize, but the vinegar solution would not, it had a honey texture. So days went by and still no progress. So after about 2 weeks I notice that the vinegar solution is starting to crystallize. What I want to know is why did it take so long for the vinegar solution to crystallize when the water solution did so quickly?