Ion-acoustic waves are destabilised in a double-plasma device by ion-beam-plasma interaction. The plasma system destabilises via a supercritical Hopf-bifurcation with the control parameter being subject to noise. This leads to erratic fluctuations between stable and oscillatory states. The experimental results, in particular the statistical properties, show that this has to be distinguished from type-I intermittency transition to chaos as reported previously for similar experimental setups.