While driving my 2019 Ford Expedition on the interstate at approximately 75 mph, the driver side seatbelt suddenly and unexpectedly locked up and forcefully retracted without warning. At the same time, there was a loud popping sound resembling a small explosion, followed by a visible puff of smoke and a noticeable odor. There was no collision or impact that would have caused the seatbelt system to activate. The seatbelt tightened forcefully against my body cause me pain and injury. The seatbelt remained locked and could no longer be moved or adjusted. This incident created a serious safety hazard because it occurred unexpectedly while I was traveling at a highway speed. The vehicle and affected seatbelt are available for inspection. The cause of the malfunction has not yet been confirmed.