I get the same acid. Sits in a plastic trash can with lid in the sun until mid afternoon. In really hot conditions (118 today). And have never seen that.
Check them first thing in the AM. If safe, open them and puncture the plastic film under the cap.
The bottles are not ventilated. I would just burp them occasionally if that's going to be an issue. I don't think you will get nearly a large enough amount of pressure to blow the bottles, anyway, but burping them should help and can't hurt. I store mine outside in a plastic bin but it's fully shaded there so I don't experience that even though it's probably hotter here at present.
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