Maggie Kieffer, 31, works at the front desk at Circle C Dental in south Austin. On Tuesday morning, she headed to work to open the office, but when she arrived, Kieffer immediately recognized that something wasn’t right. There was acid-smelling smoke, and they discovered the toilet had exploded. Austin’s fire department’s theory was that the ceiling vent overheated, caught fire and dropped onto the toilet seat, which started to burn. Lightning causes the same type of damage to a toilet in Oklahoma. No one was injured.