  From a consistent Kaluza-Klein truncation of 11-dimensional supergravity over
AdS_4 x CP^3 x S^1/Z_k, with a general 4-form ansatz, we arrive at a set of
equations and solutions for the included fields. In particular, we have a bulk
equation for a self-interacting (pseudo)scalar with arbitrary mass. By
computing the energy-momentum tensors of the associated Einstein equations, to
include the backreaction, and setting them to zero, we solve the resulting
equations with the bulk one and get solutions corresponding to marginal and
marginally relevant deformations of the boundary CFT_3, which break the
conformal symmetry. These bulk (pseudo)scalars are SU(4) x U(1)-singlet and the
corresponding solutions break all supersymmetries and parity because of the
associated (anti)M-branes wrapping around specific and mixed internal and
external directions. As a result and according to AdS_4/CFT_3 duality rules, we
would realize the boundary counterpart in three-dimensional Chern-Simon U(N)
field theories with matters in fundamental representations. In particular, we
build a SO(4)-invariant Fubini-like instanton solution by setting a specific
boundary Lagrangian. The resulting solution is used to describe the dynamics of
thin-wall bubbles that cause instability and big crunch singularities in the
bulk because of the unboundedness of the boundary double-hump potential from
below. Relations to mass-deformed ABJM model, O(N) vector models and scale
invariance breaking are also discussed. Meanwhile, we evaluate corrections for
the background actions because of the bulk and boundary instantons.
