The closest spread to peanut butter I've found in terms of flavor and texture is sunflower seed butter. It's also relatively easy to find; I've seen it in large chain grocery stores right next to the peanut butter.
A curmudgeon with years of practice. The bubbles in boiling water are steam or vaporized water. The bubbles initially do not reach the surface of the billing fluid as the colder water away from the hot bottom cools the steam turning it back to liquid. WHen all the water is at 100oC the bubbles reach the top.
When bringing liquid to a boil over a burner, the first sign of that impending boil is very small bubbles atop the liquid at the very edge of the pan; if you're heating milk, this is called scalding the milk. Next, bubbles will begin to rise from the interior of the pan, popping on the surface.