An abrupt temperature increase induced by the interaction of "curved" diffusion flames is studied experimentally. The main purpose is to reproduce and measure the numerically predicted unsteady behavior of interacting flames experimentally. A pair of curved non-premixed (i.e., diffusion) flames, which was made by four slot burners (two combined counter flow burners), is utilized. Curved flames are either formed over the fuel stream (normal diffusion flame) or oxidizer stream (inverse diffusion flame) depending on the condition, and their interaction is demonstrated. The characteristics of the ignition-like behavior, namely, a time-sequential change in sound and luminescence from the image generated by the flame fluctuation, are acquired by a microphone and a high-speed camera, respectively. From the periodic unsteady behavior of interacting flames, the ignition-like behavior is successfully confirmed in the experiment. The observed change of frequency of the ignition-like behavior against the bulk velocity gradient agrees with that predicted previously in the numerical analysis.