Carrier/rack problems of the 2018 Kia Motor Soul

Around 11:40pm on 12/3/2019 I parked my car in an empty parking lot - car was stationary. It was 51 degrees out and cloudy, but no rain or any precipitation. The car was not running; the heat/ac were not on. No one was around. Suddenly, the windshield in the back (large hatch door window) shattered entirely. It sounded like a shot. Nothing fell on the car, no people or animals were around. The whole window was shattered and crumbling along the edges. No rocks, bbs, pellets, branches, balls, or other objects anywhere. No other damage made at that moment to the car at all. The pane stayed together until I opened/closed my driver side door. Then it started to fall apart. No evidence of foul play. Only 12,600 miles on the car. Checked with the police, but no similar incidents had been reported. Occurred in kirkland, wa. No previous accidents as far as I know. Except a few weeks prior, on the highway during rush hour, a lon crack appeared on the drivers side of the front windshield, starting from the top edge about 9" long. No evidence of rock, debris, or impact.