Did You Hear or Feel The Mysterious Boom in Grand Rapids Saturday? So did you feel or hear the big boom on Saturday morning somewhere between 6 and 7 am? (The wide time frame is because accounts of the happening have had varied times reported.) Users on both the 'Nextdoor' app and Facebook’s group “We Are Westsiders” were talking about hearing a loud boom and plenty of people also talked about how it rattled their windows, shook their house, or startled them or their pets. The original post from Thomas Konieczki on the "We Are Westsiders" Facebook group, “Just heard a loud explosion over here on the West side I live over on 3rd anybody else hear that pretty loud”