Engine Noise problems of the 2016 Chevrolet Impala

For the past 3 mo. Upon starting the vehicle I hear a "pop" noise. It only happens every once in a while in the morning or the evening when I get off work. Sometimes it will go a week or more without making the sound. The sound will not repeat itself if I immediately turn the car off and restart it. The 1st time I took it to the dealership, they siad nothing was wrong & they didn't hear the "pop". The 2nd time they said it was the exhaust so they repalced some hoses, the 3rd time, in which the "pop" was more frequent and louder, they said it was the starter sticking. After replacing the starter, a week later, I still hear the "pop" upon starting it. The vehicle is not in motion when this happens. Obviously, they don't know what the problem is if they diagnosed it as the exhaust first & then the starter and it's still making the same noise after servicing both said problems. I am very frightened about this problem because 7 mo. Ago my Buick park Ave caught fire on me in my garage upon starting it and hearing the same "pop" noise. A coworker of mine has the same kind of car and is experiencing the same problem. I am almost sure we aren't the only two consumers who is experiencing this issue. I purchased the carm on 04/07/2017 and this problem started about the 1st to 2nd week in August after my 1st oil change. Please look into this, too many cars are catching fire and people are being hurt and even killed.