Happened to me once on a LX day flight ZRH-JFK , very strong winds it felt quite uncomfortable (although I fly a lot and do not mind turbulences). FA asked everybody to close shades.
The pilot started changing engine thrust constantly, where sometimes it felt like he shut them off as it was very silent, while then going full throttle the next moment and the engine sound was as loud as when the airplane is taking off. It was quite unusual. no further explanation give by the FA or pilot, all FA's were in their jumpseats.