I got some Dave's Insanity Sauce a few years ago when Asda sold it for a while. I'd got used to Encona, and the first time I had some of the insanity sauce I gave myself palpitations. It's an extract based sauce unlike the encona which is whole chilli based, so is considerably hotter than the chillis it's made from.
Since then I've had similar but less severe effects with the Bhut Jolikas (AKA Naga or ghost chilli) I got from Tesco, as I've learned to be more cautious. Bhuts/Nagas are a whole order of magnitude hotter than Scotch Bonnets. Have a small one chopped raw in a salad if you don't believe me!