  We unveil an unexpected non-Hermitian phenomenon, dubbed edge burst, in
non-Hermitian quantum dynamics. Specifically, in a class of non-Hermitian
quantum walk in periodic lattices with open boundary condition, an
exceptionally large portion of loss occurs at the system boundary. The physical
origin of this edge burst is found to be an interplay between two unique
non-Hermitian phenomena: non-Hermitian skin effect and imaginary gap closing.
Furthermore, we establish a universal bulk-edge scaling relation underlying the
non-Hermitian edge burst. Our predictions are experimentally accessible in
various non-Hermitian systems including quantum-optical and cold-atom
platforms.
