I had one near where I used to live in SoCal. On multiple occasions I got off the bike to check if my back tire was rubbing the frame of the brake pads or something. Nope. Just this weird stretch of road with no apparent slope or wind that just sucks.
Later on, I found a portion of Highway 395 in Oregon that for some reason was fast in both directions. I'd hit 20mph without much effort on the outbound and homeward legs of rides.