  We propose a mechanism for liquid formation in strongly correlated lattice
systems. The mechanism is based on an interplay between long-range attraction
and superexchange processes. As an example, we study dipolar bosons in
one-dimensional optical lattices. We present a perturbative theory and validate
it in comparison with full density-matrix renormalization group simulations for
the energetic and structural properties of different phases of the system,
i.e., self-bound Mott insulator, liquid, and gas. We analyze the nonequilibrium
properties and calculate the dynamic structure factor. Its structure differs in
compressible and insulating phases. In particular, the low-energy excitations
in compressible phases are linear phonons. We extract the speed of sound and
analyze its dependence on dipolar interaction and density. We show that it
exhibits a nontrivial behaviour owing to the breaking of Galilean invariance.
We argue that an experimental detection of this previously unknown quantum
liquid could provide a fingerprint of the superexchange process and open
intriguing possibilities for investigating non-Galilean invariant liquids.
