You may have seen these on YouTube.
The secret to doing this is a process called "supercooling". What the YouTubers do is leave a bottle of soda outdoors overnight on those nights when the temperature slowly falls a few degrees below 32 degrees Fahrenheit / 0 degrees Celsius.
It is actually possible to s-l-o-w-l-y cool something to a temperature just below its normal freezing point. As long as the container is undisturbed, it is possible for a liquid to be "supercooled".
Then what they do, is to "tap" the bottle. This causes a few nuclei of frozen liquid to form inside the supercooled bottle of soda. Once this happens, the freezing process takes place comparatively quickly -- so that it looks like it is instantly freezing.
Hope this helps.
Something involving liquid nitrogen or dry ice?