Earth is a (reasonably) gas tight container filled with flowing liquid (lava propelled by convection currents). Europa (the moon) is a reasonably gas-tight container filled with water under an ice sheet.

Of course Earth also has appreciable gravity. The real problem isn't that nature produces no gas tight liquid-filled containers, it's that gravity is the primary mechanism by which things are naturally created in space. Asking for a situation without gravity virtually requires artificial construction.