Answer: The bubbles in the boiling water is gaseous water.
Step-by-step explanation:
The conversion of water into its vapors is a physical change.
Physical change is defined as the change in which, change in shape, size etc.. takes place. No new substance gets formed in these reactions.
For Example: Melting of ice
Vaporization is defined as the physical process in which liquid particles get converted to gaseous particles.

When water is boiling for 30 minutes, the water particles are getting converted to water vapors.
Hence, the bubbles in the boiling water is gaseous water.