It has a very unique bite because of this *proteolytic* enzyme it contains (when fresh),

https://en.wikipedia.org/wiki/Bromelain

It's literally trying, and mostly failing, to digest your tongue.

One other very unique one is the Sichuan pepper, which is not a "spicy pepper" in the conventional, capsaicin sense, rather an idiosyncratic chemical that's... Wikipedia calls it "tingling, numbing":

https://en.wikipedia.org/wiki/Sichuan_pepper