  Presence of large-scale surface magnetic field in early-type stars leads to
several unique electromagnetic phenomena producing radiation over X-ray to
radio bands. Among them, the rarest type of emission is electron cyclotron
maser emission (ECME) observed as periodic, circularly polarized radio pulses.
The phenomenon was first discovered in the hot magnetic star CU Vir. Past
observations of this star led to the consensus that the star produces only
right circularly polarized ECME, suggesting that only one magnetic hemisphere
takes part in the phenomenon. Here we present the first ultra-wideband (0.4$-$4
GHz) study of this star using the upgraded Giant Metrewave Radio telescope and
the Karl G. Jansky Very Large Array, which led to the surprising discovery of
ECME of both circular polarizations up to around 1.5 GHz. The GHz observations
also allowed us to infer that the upper ECME cut-off frequency is at $\gtrsim
5\,\mathrm{GHz}$. The sub-GHz observation led to the unexpected observation of
more than two pairs of ECME pulses per rotation cycle. In addition, we report
the discovery of a `giant pulse', and transient enhancements, which are
potentially the first observational evidence of `centrifugal breakout' of
plasma from the innermost part of the stellar magnetosphere. The stark contrast
between the star's behavior at GHz and sub-GHz frequencies could either be due
to propagation effects, a manifestation of varying magnetic field topology as a
function of height, or a signature of an additional `ECME engine'.
