Before revision:  We find the existence of a set of bifurcations controlled by the relative influence of noise traders with respect to rational investors that separate a normal regime of the price dynamics to a phase punctuated by recurrent exponentially explosive bubbles. The transition to a bubble regime is favored by noise traders who are more social, and who use more momentum trading with shorter time horizons .
After revision:  By contrast to previous models in the field, we do not allow agents to switch between trading strategies. Allowing for random time-varying herding propensity, we are able to reproduce several stylized facts of financial markets such as a fat-tail distribution of returns, volatility clustering and transient faster-than-exponential bubble growth with approximate log-periodic behavior .