I bought a rather large pot of hummus the other day from Asda, a somewhat-less-than-super market, which had been reduced to 15p. Two possible reasons for such apparent good value were an imminent best before date and the fact it was reduced-fat hummus.
Unfortunately, however, it turned out to be 15p badly spent; in fact rarely have I ever spent 15 pence so unwisely: the very next day when I went to the fridge to look at my hummus, it had grown in size twofold and had burst its container. Upon closer oral examination, there was a quiet but continuous effervescing noise as a perpetual slurry of hummus and gas slowly oozed out of the container. I promptly discarded the said container and associated mess.
Is such behavior normal for hummus?
No.
Possibly the supermarket houmous contained non-traditional ingredients in order to reduce the fat content.
Adding live yoghurt to houmous you brew yourself may help preserve it.