Until recently, the Russian market near me sold date paste. It was cheap and delicious. Naturally, they stopped selling it. I had a hunch and checked in the Arab-ish market. I quickly found date syrup. When I got the stuff home, I found that both bottles were bulging. When I unscrewed the lids, the vacuum seal covers popped from the inside. A quick Google reveals that date syrup often ferments (which would explain the bulging) but should be safe to eat. The syrup smells okay. There is no obvious contamination and the stuff has a liquid consistency.
When in doubt, throw it out. Any packaged food with a bulging package trips my “danger” meter. Hard. Unless you are stranded on a desert island and the syrup is the only calories you have available, I would just toss it.
I would toss it without a moment’s hesitation. Better safe than sorry, and you have no way of knowing whether it’s fermented or worse.
Besides, if it is indeed fermented, it’s not going to taste the way you want it to.
Throw it out, don’t eat it because that would be the worst super hero origin story EVER.
While I’d suggest that the OP discard his purchase, I’ll admit that I’d consume it without a second thought,
Kimchee usually erupts on opening, as does the unpasteurized apple cider the local orchard sells. Cider is fine with a mild “ting”. You can make wine from date syrup.
I was going to say the same thing.
A couple weeks ago, I bought some sausage on sale and put it in the freezer, and then thawed it in the fridge and got it out last night to cook it. Upon smelling it, I put that rule to the test, and tossed it in my nearby creek for the wildlife.
Recently I took a jar of homemade fig preserves out of the fridge. I had enjoyed multiple helpings of it but hadn’t touched the jar for a month or two. The recipe included quite a bit of sugar, which normally deters the growth of microorganisms.
This time when I unscrewed the lid, what looked like a fine steam arose from the surface, followed by prodigious bubbles all through the contents.
It still smelled fine, but I wanted no part of whatever process was going on in there, and tossed it. 
Google will tell you anything and everything. What site is the info coming from?
He Who Dwells Beneath The Figs
Carbonated jam!
I once bought some non-dairy yogurt on sale (IIRC, it was CocoYo which I do still see for sale) and while it tasted OK, it had a weird texture that suggested it too had a bit of carbonation. I discarded the yogurt, and use the jar for quarters for the laundry room. My brother does like it, mixed in with some kefir, which is also mildly carbonated, but it’s supposed to be.
