A xenon strobe tube is a high voltage device. Power for the tube is around 200 to 300 volts depending on the tube. The flash is triggered by a much higher voltage. The tube will have a metal band around it or a wire wrapped around it. That is connected to a trigger transformer which produces a short pulse in the 4,000 to 10,000 volt range. Again, the exact voltage depends on the specifications for the tube.
The popping noise in a phone is that it is picking up the electric field produced by the high voltage discharge used to fire the tube. Whether a phone is effected depends on the circuitry and shielding in the phone.
Tutorial on xenon flash tubes.
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Thank you Bill Nye the fire alarm science guy