I made peanut brittle for the holidays last week and sampled my fair share.  That night, I had a bad reaction to it (sour stomach, diarrhea and intestinal gas). 

I cleared the peanut brittle in the morning.  That night I had another sampling and had no adverse reaction.  The next night, I had my fair share of caramel popcorn and got sick in the same way again.  The next day, I cleared the caramel popcorn and the next night ate more.  Again, I had no bad reaction.