Bubble universe

The bubble universe was a tiny universe which was home to the sentient planetoid known as House. House lured Time Lords from the main universe through the bubble universe rift so it could consume their TARDISes. The Doctor and various other Time Lords were once drawn to the bubble universe by false distress hypercubes. The bubble universe was destroyed soon after House left it inside of the Doctor's TARDIS. (DW: The Doctor's Wife)