  We systematically study the holographic phase transition of the radion field
in a five-dimensional warped model which includes a scalar potential with a
power-like behavior. We consider Kaluza-Klein (KK) resonances with masses
$m_{\rm KK}$ at the TeV scale or beyond. The backreaction of the radion field
on the gravitational metric is taken into account by using the superpotential
formalism. The confinement/deconfinement first order phase transition leads to
a gravitational wave stochastic background which mainly depends on the scale
$m_{\rm KK}$ and the number of colors, $N$, in the dual theory. Its power
spectrum peaks at a frequency that depends on the amount of tuning required in
the electroweak sector. It turns out that the present and forthcoming
gravitational wave observatories can probe scenarios where the KK resonances
are very heavy. Current aLIGO data already rule out vector boson KK resonances
with masses in the interval $m_{\rm KK}\sim(1 - 10) \times 10^5$ TeV. Future
gravitational experiments will be sensitive to resonances with masses $m_{\rm
KK}\lesssim 10^5$ TeV (LISA), $10^8$ TeV (aLIGO Design) and $10^9$ TeV (ET).
Finally, we also find that the Big Bang Nucleosynthesis bound in the frequency
spectrum turns into a lower bound for the nucleation temperature as $T_n
\gtrsim 10^{-4}\sqrt{N} \,m_{\rm KK}$.
