About your broken glass:
Did you use canning jars? If so, it was likely you tightened the lids too much. This is mentioned on the Chefsteps site in their recipes that the lids should be barely tight - finger-tight they call it. It will let excess air escape that expands with heat and won’t let water in. I have only had one case where water got in and that was because the jar tumbled upside down, and I have never had a jar break on me.
Make sure when you submerge it, some small bubbles come out. This will indicate you tightened the lids properly.
Also, your plastic tub - I would check its properties. The only food safe plastic is polypropylene, which is number 5 on the recycling label. If your lid is flexible like that one, it has to be silicone; if it is plastic, it is not polypropylene (PP is not flexible or soft). Soft plastics will leech potentially dangerous chemicals in your food over time.