In stage performances, an invisible wall in front of the stage often weakens the connections between the audience and performers. To amplify this performative connection, we present the concept "Boiling Mind". Our design concept is based on streaming sensor data related to heart and electrodermal activities from audience members and integrating this data into staging elements, such as visual projections, music, and lighting. Thus, the internal states of the audience directly influence the staging. Artists can have a more direct perception of the inner reactions of audience members and can create physical expressions in response to them. In this paper, we present the wearable sensing system as well as design considerations of mapping heart and electrodermal activity to changes in the staging elements. We evaluated our design and setup over three live performances.