I have this right before I wake up, sometimes. If you're in no danger of waking up, have you tried opening a portal?

IMO, this requires a bit of preparation. Throughout the day and before you go to bed, visualize opening a portal/teleporting/disolving the dream/whatever method appeals to you. For instance, visualize cutting open a hole in the dreamscape, making a portal to another place with a bit more substance. Daydreaming about it tends to help me.