Popping sound and bubbles in extruded filament most probably is due to the filament is moist.
1) Preventing moist filament
Remove unused filament from the 3D printer, keep it in a ziplock bag with some silica gel bags. This will able to prevent the filament being moist too fast.
We suggest to get some ziplock bag from Daiso, it is pretty handy in this case.
2) Dry the filament
Some user use a food dehydrator to dry the filament. We’ve never tried it yet, here are a guide that we found online on how hot and how long to dry the filament for your reference, the actual time and temperature still very depending on your food dehydrator.
Smimilar article:
https://www.filamently.com/post/humidity-a-silent-killer-of-pla-3d-printer-filament
Tell us how you prevent your filament from moist and how your dry them if they are moist in the comment.
Drying filament with food dehydrator
| Filament | Temperature | Hours |
| PEEK | 100° c | 4 hours |
| PPS | 95° c | 3 hours |
| PA | 80° c | 2 hours |
| PC PBT | 80° | 2 hours |
| PC | 80° c | 2 hours |
| PMMA | 80° c | 3 hours |
| ABS | 65° | 2 hours |
| PETG | 65° c | 2 hours |
| PLA | 50° C | 1 hours |
| TPU | 70° c | 2 hours |
| TPE | 70° c | 2 hours |
| TPA | 70° c | 2 hours |
| WPC | 65° c | 3 hours |