It sounds like it was carbed up more than beer is, and that the bottles weren't capable of holding the higher carbonation of soda.
Beer is carbonated to 2.2-2.5 volumes of co2, typically, while soda is carbed to more like 4 volumes (or more).
Soda used to come in glass bottles when I was a kid- very solid, thick, heavy glass. Plastic is more common now, and holds more pressure than thin glass.
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